Carpometacarpal and metacarpophalangeal joint collapse is associated with increased pain but not functional impairment in persons with thumb carpometacarpal osteoarthritis.

Abstract Introduction Due to the complex shape of the carpometacarpal (CMC) joint, a fixed joint collapse deformity of the thumb CMC (CMC1) and metacarpophalangeal (MCP1) joint can present in the advanced stages of CMC1 osteoarthritis (OA), resulting in adduction of the first metacarpal (MC) and hyperextension of the MCP1. The aim of this study was to determine whether joint collapse deformity is associated with worse pain and/or functional impairment. Methods This study used baseline data from the COMBO study (Efficacy of combined conservative therapies on clinical outcomes in patients with CMC1 OA). Joint collapse was determined by the study assessor at baseline during the tip-pinch test using a pinch gauge. Pain was assessed on a Visual Analogue Scale (0-100) and function was assessed using the Functional Index for Hand Osteoarthritis questionnaire (0-30). Pain and function, and the presence of joint collapse were entered in a univariate logistic regression. The final adjusted model for pain and joint collapse included age and sex. The final adjusted model for function and joint collapse included Kellgren Lawrence Grade (KLG) and grip strength. Results Data from 140 participants were included in the analysis. About 20% of participants demonstrated joint collapse on the tip-pinch test. The presence of joint collapse was associated with increased pain in the unadjusted [p=0.047, OR=2.45, 95% CI (1.01, 5.910] and adjusted model [p=0.049, OR = 2.45, 95% CI (1.00, 5.98)]. Conclusion CMC1 patients with joint collapse reported increased pain compared to those without joint collapse. Future studies are needed to determine the relationship between thumb hypermobility and joint collapse and how to manage these conditions effectively.